Selaginella hansenii
Selaginella acanthonota
Hansen's spike-moss
sandy spike-moss, spiny spike-moss
not readily fragmenting, prostrate, upperside and underside structurally different, irregularly forked, branches determinate, tips upturned.
radially symmetric, underground (rhizomatous) and aerial, not readily fragmenting, irregularly forked; rhizomatous and aerial stems often with 1 branch arrested, budlike, tips straight; rhizomatous stems with budlike branches, these sometimes inconspicuous;
aerial stems erect or ascending, lateral branches conspicuously determinate.
with underside leaves slightly longer and narrower than upperside leaves, otherwise monomorphic, not clearly ranked, tightly appressed, ascending, green or green with red spots, or reddish, linear-lanceolate (underside) to linear-triangular (upperside), (2–)3–4.5 × 0.5–0.6 mm;
abaxial ridges present;
base abruptly adnate, pubescent (sometimes glabrous);
margins ciliate, cilia white to white opaque, strongly appressed and ascending, 0.03–0.1 mm;
apex with bristle white to white-opaque, 0.5–1.4 mm (those on underside leaves sometimes 1/4–1/2 longer than those on upperside leaves).
monomorphic, in pseudowhorls of 4 or 5, tightly appressed, ascending, green, narrowly triangular-lanceolate or narrowly lanceolate, 2–3.25 × 0.4–0.6(–0.7) mm;
abaxial ridges present;
base rounded to cuneate, slightly decurrent to adnate, pubescent;
margins ciliate, cilia transparent, spreading at base, dentiform, ascending toward apex, 0.02–0.1 mm;
apex plane, attenuate or seldom slightly keeled;
bristle white or whitish to transparent, sometimes with brownish to reddish band at base marking breaking point (in old leaves), straight, puberulent, (0.35–)0.5–1.4 mm.
solitary, 5–7 mm;
sporophylls ovate-deltate to ovate-triangular, abaxial ridges not prominent, base glabrous, margins short-ciliate, apex bristled.
solitary, (0.5–)1–3(–3.5) cm;
sporophylls ovate-lanceolate to lanceolate, abaxial ridges not prominent, base pubescent, margins ciliate, apex bristled.
borne on upperside of stems, throughout stem length, 0.25–0.45 mm diam.
borne on upperside of stems, restricted to rhizomatous stems or lowermost base of aerial stems (seldom on distal 2/3, if so, short), mostly aerial, 0.25–0.43 mm diam.
Selaginella hansenii
Selaginella acanthonota
Leaf dimorphism in Selaginella hansenii is only slightly and inconsistently expressed; the upperside leaves tend to be more lanceolate, short, and slightly thick, whereas the underside leaves tend to be more linear, longer, and thinner, but in some specimens the leaves are monomorphic. Red leaves are rare within Selaginella subg. Tetragonostachys, otherwise found in the flora only occasionally in S. rupestris. Such leaves are more common in S. steyermarkii Alston from southern Mexico and Guatemala and S. sartorii Hieronymus from Mexico.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Selaginella acanthonota is a member of the S. arenicola complex, a taxonomically difficult group. Specimens of S. acanthonota from the northern part of its range (e.g., North Carolina, South Carolina, and Georgia) tend to have rather prostrate underground (rhizomatous) stems, with ascending to erect, short aerial stems. Those from Florida have rather ascending underground (rhizomatous) stems and more slender aerial stems. Selaginella acanthonota, in addition to features given in the description, is characterized by having hairs running lengthwise along or at least to the proximal half of the ridges bordering the abaxial groove of the leaves and sporophylls, and, usually, puberulent leaves and sporophyll apices. The hairs on the ridges sometimes break off easily or are somewhat enclosed within the abaxial groove (when the ridges close as a response to dryness), but they can be seen under a microscope. More systematic studies are needed within S. acanthonota and the entire S. arenicola complex.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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